/*

 * (C) Copyright IBM Corporation 2006

 * All Rights Reserved.

 * Copyright 2012 Red Hat, Inc.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * on the rights to use, copy, modify, merge, publish, distribute, sub

 * license, and/or sell copies of the Software, and to permit persons to whom

 * the Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the next

 * paragraph) shall be included in all copies or substantial portions of the

 * Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL

 * IBM AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

 * DEALINGS IN THE SOFTWARE.

 */

/**

 * \file linux_sysfs.c

 * Access PCI subsystem using Linux's sysfs interface.  This interface is

 * available starting somewhere in the late 2.5.x kernel phase, and is the

 * preferred method on all 2.6.x kernels.

 *

 * \author Ian Romanick <idr@us.ibm.com>

 */

#define _GNU_SOURCE

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <stdlib.h>

#include <string.h>

#include <stdio.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <limits.h>

#include <sys/mman.h>

#include <dirent.h>

#include <errno.h>

#if defined(__i386__) || defined(__x86_64__) || defined(__arm__)

#include <sys/io.h>

#else

#define inb(x) -1

#define inw(x) -1

#define inl(x) -1

#define outb(x,y) do {} while (0)

#define outw(x,y) do {} while (0)

#define outl(x,y) do {} while (0)

#define iopl(x) -1

#endif

#ifdef HAVE_MTRR

#include <asm/mtrr.h>

#include <sys/ioctl.h>

#endif

#include "pciaccess.h"

#include "pciaccess_private.h"

#include "linux_devmem.h"

static const struct pci_system_methods linux_sysfs_methods;

#define SYS_BUS_PCI "/sys/bus/pci/devices"

static int

pci_device_linux_sysfs_read( struct pci_device * dev, void * data,

			     pciaddr_t offset, pciaddr_t size,

			     pciaddr_t * bytes_read );

static int populate_entries(struct pci_system * pci_sys);

/**

 * Attempt to access PCI subsystem using Linux's sysfs interface.

 */

_pci_hidden int

pci_system_linux_sysfs_create( void )

{

    int err = 0;

    struct stat st;

    /* If the directory "/sys/bus/pci/devices" exists, then the PCI subsystem

     * can be accessed using this interface.

     */

    if ( stat( SYS_BUS_PCI, & st ) == 0 ) {

	pci_sys = calloc( 1, sizeof( struct pci_system ) );

	if ( pci_sys != NULL ) {

	    pci_sys->methods = & linux_sysfs_methods;

#ifdef HAVE_MTRR

	    pci_sys->mtrr_fd = open("/proc/mtrr", O_WRONLY | O_CLOEXEC);

#endif

	    err = populate_entries(pci_sys);

	}

	else {

	    err = ENOMEM;

	}

    }

    else {

	err = errno;

    }

    return err;

}

/**

 * Filter out the names "." and ".." from the scanned sysfs entries.

 *

 * \param d  Directory entry being processed by \c scandir.

 *

 * \return

 * Zero if the entry name matches either "." or ".."

 *

 * \sa scandir, populate_entries

 */

static int

scan_sys_pci_filter( const struct dirent * d )

{

    return !((strcmp( d->d_name, "." ) == 0)

	     || (strcmp( d->d_name, ".." ) == 0));

}

static int

parse_separate_sysfs_files(struct pci_device * dev)

{

    static const char *attrs[] = {

      "vendor",

      "device",

      "class",

      "revision",

      "subsystem_vendor",

      "subsystem_device",

    };

    char name[256];

    char resource[512];

    uint64_t data[6];

    int fd;

    int i;

    for (i = 0; i < 6; i++) {

	snprintf(name, 255, "%s/%04x:%02x:%02x.%1u/%s",

		 SYS_BUS_PCI,

		 dev->domain,

		 dev->bus,

		 dev->dev,

		 dev->func,

		 attrs[i]);

	fd = open(name, O_RDONLY | O_CLOEXEC);

	if (fd == -1) {

	    return errno;

	}

	read(fd, resource, 512);

	resource[511] = '\0';

	close(fd);

	data[i] = strtoull(resource, NULL, 16);

    }

    dev->vendor_id = data[0] & 0xffff;

    dev->device_id = data[1] & 0xffff;

    dev->device_class = data[2] & 0xffffff;

    dev->revision = data[3] & 0xff;

    dev->subvendor_id = data[4] & 0xffff;

    dev->subdevice_id = data[5] & 0xffff;

    return 0;

}

int

populate_entries( struct pci_system * p )

{

    struct dirent ** devices = NULL;

    int n;

    int i;

    int err = 0;

    n = scandir( SYS_BUS_PCI, & devices, scan_sys_pci_filter, alphasort );

    if ( n > 0 ) {

	p->num_devices = n;

	p->devices = calloc( n, sizeof( struct pci_device_private ) );

	if (p->devices != NULL) {

	    for (i = 0 ; i < n ; i++) {

		uint8_t config[48];

		pciaddr_t bytes;

		unsigned dom, bus, dev, func;

		struct pci_device_private *device =

			(struct pci_device_private *) &p->devices[i];

		sscanf(devices[i]->d_name, "%x:%02x:%02x.%1u",

		       & dom, & bus, & dev, & func);

		device->base.domain = dom;

		/*

		 * Applications compiled with older versions  do not expect

		 * 32-bit domain numbers. To keep them working, we keep a 16-bit

		 * version of the domain number at the previous location.

		 */

		if (dom > 0xffff)

		     device->base.domain_16 = 0xffff;

		else

		     device->base.domain_16 = dom;

		device->base.bus = bus;

		device->base.dev = dev;

		device->base.func = func;

		err = parse_separate_sysfs_files(& device->base);

		if (!err)

		    continue;

		err = pci_device_linux_sysfs_read(& device->base, config, 0,

						  48, & bytes);

		if ((bytes == 48) && !err) {

		    device->base.vendor_id = (uint16_t)config[0]

			+ ((uint16_t)config[1] << 8);

		    device->base.device_id = (uint16_t)config[2]

			+ ((uint16_t)config[3] << 8);

		    device->base.device_class = (uint32_t)config[9]

			+ ((uint32_t)config[10] << 8)

			+ ((uint32_t)config[11] << 16);

		    device->base.revision = config[8];

		    device->base.subvendor_id = (uint16_t)config[44]

			+ ((uint16_t)config[45] << 8);

		    device->base.subdevice_id = (uint16_t)config[46]

			+ ((uint16_t)config[47] << 8);

		}

		if (err) {

		    break;

		}

	    }

	}

	else {

	    err = ENOMEM;

	}

    }

    for (i = 0; i < n; i++)

	free(devices[i]);

    free(devices);

    if (err) {

	free(p->devices);

	p->devices = NULL;

    }

    return err;

}

static int

pci_device_linux_sysfs_probe( struct pci_device * dev )

{

    char     name[256];

    uint8_t  config[256];

    char     resource[512];

    int fd;

    pciaddr_t bytes;

    unsigned i;

    int err;

    struct stat  st;

    err = pci_device_linux_sysfs_read( dev, config, 0, 256, & bytes );

    if ( bytes >= 64 ) {

	struct pci_device_private *priv = (struct pci_device_private *) dev;

	dev->irq = config[60];

	priv->header_type = config[14];

	/* The PCI config registers can be used to obtain information

	 * about the memory and I/O regions for the device.  However,

	 * doing so requires some tricky parsing (to correctly handle

	 * 64-bit memory regions) and requires writing to the config

	 * registers.  Since we'd like to avoid having to deal with the

	 * parsing issues and non-root users can write to PCI config

	 * registers, we use a different file in the device's sysfs

	 * directory called "resource".

	 *

	 * The resource file contains all of the needed information in

	 * a format that is consistent across all platforms.  Each BAR

	 * and the expansion ROM have a single line of data containing

	 * 3, 64-bit hex values:  the first address in the region,

	 * the last address in the region, and the region's flags.

	 */

	snprintf( name, 255, "%s/%04x:%02x:%02x.%1u/resource",

		  SYS_BUS_PCI,

		  dev->domain,

		  dev->bus,

		  dev->dev,

		  dev->func );

	fd = open( name, O_RDONLY | O_CLOEXEC);

	if ( fd != -1 ) {

	    char * next;

	    pciaddr_t  low_addr;

	    pciaddr_t  high_addr;

	    pciaddr_t  flags;

	    bytes = read( fd, resource, 512 );

	    resource[511] = '\0';

	    close( fd );

	    next = resource;

	    for ( i = 0 ; i < 6 ; i++ ) {

		dev->regions[i].base_addr = strtoull( next, & next, 16 );

		high_addr = strtoull( next, & next, 16 );

		flags = strtoull( next, & next, 16 );

		if ( dev->regions[i].base_addr != 0 ) {

		    dev->regions[i].size = (high_addr

					    - dev->regions[i].base_addr) + 1;

		    dev->regions[i].is_IO = (flags & 0x01);

		    dev->regions[i].is_64 = (flags & 0x04);

		    dev->regions[i].is_prefetchable = (flags & 0x08);

		}

	    }

	    low_addr = strtoull( next, & next, 16 );

	    high_addr = strtoull( next, & next, 16 );

	    flags = strtoull( next, & next, 16 );

	    if ( low_addr != 0 ) {

		priv->rom_base = low_addr;

	    }

	}

    }

    snprintf( name, 255, "%s/%04x:%02x:%02x.%1u/rom",

	      SYS_BUS_PCI,

	      dev->domain,

	      dev->bus,

	      dev->dev,

	      dev->func );

    fd = open( name, O_RDWR );

    if ( fd == -1 ) {

	dev->rom_size = 0x10000;

    } else if ( fstat( fd, & st ) == -1 ) {

	close( fd );

	dev->rom_size = 0x10000;

    } else {

	close( fd );

	dev->rom_size = st.st_size == 0 ? 0x10000 : st.st_size;

    }

    return err;

}

static int

pci_device_linux_sysfs_read_rom( struct pci_device * dev, void * buffer )

{

    char name[256];

    int fd;

    struct stat  st;

    int err = 0;

    size_t total_bytes;

    snprintf( name, 255, "%s/%04x:%02x:%02x.%1u/rom",

	      SYS_BUS_PCI,

	      dev->domain,

	      dev->bus,

	      dev->dev,

	      dev->func );

    fd = open( name, O_RDWR | O_CLOEXEC);

    if ( fd == -1 ) {

#ifdef LINUX_ROM

	/* If reading the ROM using sysfs fails, fall back to the old

	 * /dev/mem based interface.

	 * disable this for newer kernels using configure

	 */

	return pci_device_linux_devmem_read_rom(dev, buffer);

#else

	return errno;

#endif

    }

    if ( fstat( fd, & st ) == -1 ) {

	close( fd );

	return errno;

    }

    /* This is a quirky thing on Linux.  Even though the ROM and the file

     * for the ROM in sysfs are read-only, the string "1" must be written to

     * the file to enable the ROM.  After the data has been read, "0" must be

     * written to the file to disable the ROM.

     */

    write( fd, "1", 1 );

    lseek( fd, 0, SEEK_SET );

    for ( total_bytes = 0 ; total_bytes < dev->rom_size ; /* empty */ ) {

	const int bytes = read( fd, (char *) buffer + total_bytes,

				dev->rom_size - total_bytes );

	if ( bytes == -1 ) {

	    err = errno;

	    break;

	}

	else if ( bytes == 0 ) {

	    break;

	}

	total_bytes += bytes;

    }

    lseek( fd, 0, SEEK_SET );

    write( fd, "0", 1 );

    close( fd );

    return err;

}

static int

pci_device_linux_sysfs_read( struct pci_device * dev, void * data,

			     pciaddr_t offset, pciaddr_t size,

			     pciaddr_t * bytes_read )

{

    char name[256];

    pciaddr_t temp_size = size;

    int err = 0;

    int fd;

    char *data_bytes = data;

    if ( bytes_read != NULL ) {

	*bytes_read = 0;

    }

    /* Each device has a directory under sysfs.  Within that directory there

     * is a file named "config".  This file used to access the PCI config

     * space.  It is used here to obtain most of the information about the

     * device.

     */

    snprintf( name, 255, "%s/%04x:%02x:%02x.%1u/config",

	      SYS_BUS_PCI,

	      dev->domain,

	      dev->bus,

	      dev->dev,

	      dev->func );

    fd = open( name, O_RDONLY | O_CLOEXEC);

    if ( fd == -1 ) {

	return errno;

    }

    while ( temp_size > 0 ) {

	const ssize_t bytes = pread64( fd, data_bytes, temp_size, offset );

	/* If zero bytes were read, then we assume it's the end of the

	 * config file.

	 */

	if (bytes == 0)

	    break;

	if ( bytes < 0 ) {

	    err = errno;

	    break;

	}

	temp_size -= bytes;

	offset += bytes;

	data_bytes += bytes;

    }

    if ( bytes_read != NULL ) {

	*bytes_read = size - temp_size;

    }

    close( fd );

    return err;

}

static int

pci_device_linux_sysfs_write( struct pci_device * dev, const void * data,

			     pciaddr_t offset, pciaddr_t size,

			     pciaddr_t * bytes_written )

{

    char name[256];

    pciaddr_t temp_size = size;

    int err = 0;

    int fd;

    const char *data_bytes = data;

    if ( bytes_written != NULL ) {

	*bytes_written = 0;

    }

    /* Each device has a directory under sysfs.  Within that directory there

     * is a file named "config".  This file used to access the PCI config

     * space.  It is used here to obtain most of the information about the

     * device.

     */

    snprintf( name, 255, "%s/%04x:%02x:%02x.%1u/config",

	      SYS_BUS_PCI,

	      dev->domain,

	      dev->bus,

	      dev->dev,

	      dev->func );

    fd = open( name, O_WRONLY | O_CLOEXEC);

    if ( fd == -1 ) {

	return errno;

    }

    while ( temp_size > 0 ) {

	const ssize_t bytes = pwrite64( fd, data_bytes, temp_size, offset );

	/* If zero bytes were written, then we assume it's the end of the

	 * config file.

	 */

	if ( bytes == 0 )

	    break;

	if ( bytes < 0 ) {

	    err = errno;

	    break;

	}

	temp_size -= bytes;

	offset += bytes;

	data_bytes += bytes;

    }

    if ( bytes_written != NULL ) {

	*bytes_written = size - temp_size;

    }

    close( fd );

    return err;

}

static int

pci_device_linux_sysfs_map_range_wc(struct pci_device *dev,

				    struct pci_device_mapping *map)

{

    char name[256];

    int fd;

    const int prot = ((map->flags & PCI_DEV_MAP_FLAG_WRITABLE) != 0)

        ? (PROT_READ | PROT_WRITE) : PROT_READ;

    const int open_flags = ((map->flags & PCI_DEV_MAP_FLAG_WRITABLE) != 0)

        ? O_RDWR : O_RDONLY;

    const off_t offset = map->base - dev->regions[map->region].base_addr;

    snprintf(name, 255, "%s/%04x:%02x:%02x.%1u/resource%u_wc",

	     SYS_BUS_PCI,

	     dev->domain,

	     dev->bus,

	     dev->dev,

	     dev->func,

	     map->region);

    fd = open(name, open_flags | O_CLOEXEC);

    if (fd == -1)

	    return errno;

    map->memory = mmap(NULL, map->size, prot, MAP_SHARED, fd, offset);

    if (map->memory == MAP_FAILED) {

        map->memory = NULL;

	close(fd);

	return errno;

    }

    close(fd);

    return 0;

}

/**

 * Map a memory region for a device using the Linux sysfs interface.

 *

 * \param dev   Device whose memory region is to be mapped.

 * \param map   Parameters of the mapping that is to be created.

 *

 * \return

 * Zero on success or an \c errno value on failure.

 *

 * \sa pci_device_map_rrange, pci_device_linux_sysfs_unmap_range

 *

 * \todo

 * Some older 2.6.x kernels don't implement the resourceN files.  On those

 * systems /dev/mem must be used.  On these systems it is also possible that

 * \c mmap64 may need to be used.

 */

static int

pci_device_linux_sysfs_map_range(struct pci_device *dev,

                                 struct pci_device_mapping *map)

{

    char name[256];

    int fd;

    int err = 0;

    const int prot = ((map->flags & PCI_DEV_MAP_FLAG_WRITABLE) != 0)

        ? (PROT_READ | PROT_WRITE) : PROT_READ;

    const int open_flags = ((map->flags & PCI_DEV_MAP_FLAG_WRITABLE) != 0)

        ? O_RDWR : O_RDONLY;

    const off_t offset = map->base - dev->regions[map->region].base_addr;

#ifdef HAVE_MTRR

    struct mtrr_sentry sentry = {

	.base = map->base,

        .size = map->size,

	.type = MTRR_TYPE_UNCACHABLE

    };

#endif

    /* For WC mappings, try sysfs resourceN_wc file first */

    if ((map->flags & PCI_DEV_MAP_FLAG_WRITE_COMBINE) &&

	!pci_device_linux_sysfs_map_range_wc(dev, map))

	    return 0;

    snprintf(name, 255, "%s/%04x:%02x:%02x.%1u/resource%u",

             SYS_BUS_PCI,

             dev->domain,

             dev->bus,

             dev->dev,

             dev->func,

             map->region);

    fd = open(name, open_flags | O_CLOEXEC);

    if (fd == -1) {

        return errno;

    }

    map->memory = mmap(NULL, map->size, prot, MAP_SHARED, fd, offset);

    if (map->memory == MAP_FAILED) {

        map->memory = NULL;

	close(fd);

	return errno;

    }

#ifdef HAVE_MTRR

    if ((map->flags & PCI_DEV_MAP_FLAG_CACHABLE) != 0) {

        sentry.type = MTRR_TYPE_WRBACK;

    } else if ((map->flags & PCI_DEV_MAP_FLAG_WRITE_COMBINE) != 0) {

        sentry.type = MTRR_TYPE_WRCOMB;

    }

    if (pci_sys->mtrr_fd != -1 && sentry.type != MTRR_TYPE_UNCACHABLE) {

	if (ioctl(pci_sys->mtrr_fd, MTRRIOC_ADD_ENTRY, &sentry) < 0) {

	    /* FIXME: Should we report an error in this case?

	     */

	    fprintf(stderr, "error setting MTRR "

		    "(base = 0x%016" PRIx64 ", size = 0x%08x, type = %u) %s (%d)\n",

		    (pciaddr_t)sentry.base, sentry.size, sentry.type,

		    strerror(errno), errno);

/*            err = errno;*/

	}

	/* KLUDGE ALERT -- rewrite the PTEs to turn off the CD and WT bits */

	mprotect (map->memory, map->size, PROT_NONE);

	err = mprotect (map->memory, map->size, PROT_READ|PROT_WRITE);

	if (err != 0) {

	    fprintf(stderr, "mprotect(PROT_READ | PROT_WRITE) failed: %s\n",

		    strerror(errno));

	    fprintf(stderr, "remapping without mprotect performance kludge.\n");

	    munmap(map->memory, map->size);

	    map->memory = mmap(NULL, map->size, prot, MAP_SHARED, fd, offset);

	    if (map->memory == MAP_FAILED) {

		map->memory = NULL;

		close(fd);

		return errno;

	    }

	}

    }

#endif

    close(fd);

    return 0;

}

/**

 * Unmap a memory region for a device using the Linux sysfs interface.

 *

 * \param dev   Device whose memory region is to be unmapped.

 * \param map   Parameters of the mapping that is to be destroyed.

 *

 * \return

 * Zero on success or an \c errno value on failure.

 *

 * \sa pci_device_map_rrange, pci_device_linux_sysfs_map_range

 *

 * \todo

 * Some older 2.6.x kernels don't implement the resourceN files.  On those

 * systems /dev/mem must be used.  On these systems it is also possible that

 * \c mmap64 may need to be used.

 */

static int

pci_device_linux_sysfs_unmap_range(struct pci_device *dev,

				   struct pci_device_mapping *map)

{

    int err = 0;

#ifdef HAVE_MTRR

    struct mtrr_sentry sentry = {

	.base = map->base,

        .size = map->size,

	.type = MTRR_TYPE_UNCACHABLE

    };

#endif

    err = pci_device_generic_unmap_range (dev, map);

    if (err)

	return err;

#ifdef HAVE_MTRR

    if ((map->flags & PCI_DEV_MAP_FLAG_CACHABLE) != 0) {

        sentry.type = MTRR_TYPE_WRBACK;

    } else if ((map->flags & PCI_DEV_MAP_FLAG_WRITE_COMBINE) != 0) {

        sentry.type = MTRR_TYPE_WRCOMB;

    }

    if (pci_sys->mtrr_fd != -1 && sentry.type != MTRR_TYPE_UNCACHABLE) {

	if (ioctl(pci_sys->mtrr_fd, MTRRIOC_DEL_ENTRY, &sentry) < 0) {

	    /* FIXME: Should we report an error in this case?

	     */

	    fprintf(stderr, "error setting MTRR "

		    "(base = 0x%016" PRIx64 ", size = 0x%08x, type = %u) %s (%d)\n",

		    (pciaddr_t)sentry.base, sentry.size, sentry.type,

		    strerror(errno), errno);

/*            err = errno;*/

	}

    }

#endif

    return err;

}

static void pci_device_linux_sysfs_enable(struct pci_device *dev)

{

    char name[256];

    int fd;

    snprintf( name, 255, "%s/%04x:%02x:%02x.%1u/enable",

	      SYS_BUS_PCI,

	      dev->domain,

	      dev->bus,

	      dev->dev,

	      dev->func );

    fd = open( name, O_RDWR | O_CLOEXEC);

    if (fd == -1)

       return;

    write( fd, "1", 1 );

    close(fd);

}

static int pci_device_linux_sysfs_boot_vga(struct pci_device *dev)

{

    char name[256];

    char reply[3];

    int fd, bytes_read;

    int ret = 0;

    snprintf( name, 255, "%s/%04x:%02x:%02x.%1u/boot_vga",

	      SYS_BUS_PCI,

	      dev->domain,

	      dev->bus,

	      dev->dev,

	      dev->func );

    fd = open( name, O_RDONLY | O_CLOEXEC);

    if (fd == -1)

       return 0;

    bytes_read = read(fd, reply, 1);

    if (bytes_read != 1)

	goto out;

    if (reply[0] == '1')

	ret = 1;

out:

    close(fd);

    return ret;

}

static int pci_device_linux_sysfs_has_kernel_driver(struct pci_device *dev)

{

    char name[256];

    struct stat dummy;

    int ret;

    snprintf( name, 255, "%s/%04x:%02x:%02x.%1u/driver",

	      SYS_BUS_PCI,

	      dev->domain,

	      dev->bus,

	      dev->dev,

	      dev->func );

    ret = stat(name, &dummy);

    if (ret < 0)

	return 0;

    return 1;

}

static struct pci_io_handle *

pci_device_linux_sysfs_open_device_io(struct pci_io_handle *ret,

				      struct pci_device *dev, int bar,

				      pciaddr_t base, pciaddr_t size)

{

    char name[PATH_MAX];

    snprintf(name, PATH_MAX, "%s/%04x:%02x:%02x.%1u/resource%d",

	     SYS_BUS_PCI, dev->domain, dev->bus, dev->dev, dev->func, bar);

    ret->fd = open(name, O_RDWR | O_CLOEXEC);

    if (ret->fd < 0)

	return NULL;

    ret->base = base;

    ret->size = size;

    ret->is_legacy = 0;

    return ret;

}

static struct pci_io_handle *

pci_device_linux_sysfs_open_legacy_io(struct pci_io_handle *ret,

				      struct pci_device *dev, pciaddr_t base,

				      pciaddr_t size)

{

    char name[PATH_MAX];

    /* First check if there's a legacy io method for the device */

    while (dev) {

	snprintf(name, PATH_MAX, "/sys/class/pci_bus/%04x:%02x/legacy_io",

		 dev->domain, dev->bus);

	ret->fd = open(name, O_RDWR | O_CLOEXEC);

	if (ret->fd >= 0)

	    break;

	dev = pci_device_get_parent_bridge(dev);

    }

    /*

     * You would think you'd want to use /dev/port here.  Don't make that

     * mistake, /dev/port only does byte-wide i/o cycles which means it

     * doesn't work.  If you think this is stupid, well, you're right.

     */

    /* If we've no other choice, iopl */

    if (ret->fd < 0) {

	if (iopl(3))

	    return NULL;

    }

    ret->base = base;

    ret->size = size;

    ret->is_legacy = 1;